具有四重氢键识别基元超支化聚合物的特殊流变行为  

UNCOMMON MELT RHEOLOGICAL BEHAVIOR OF HYPERBRANCHED POLYMERS BEARING QUADRUPLE HYDROGEN BONDING UNITS

作　　者：李勃天[1] 唐黎明[1] 邱义鹏[1] 王宇[1] 

机构地区：[1]清华大学化工系教育部先进材料重点实验室,北京100084

出　　处：《高分子学报》2009年第6期581-585,共5页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号20574041;20874055;20204005)资助项目

摘　　要：在羟基与异氰酸酯基官能团比1∶0.13、1∶0.25、1∶0.33和1∶0.5下,通过端羟基超支化聚(酯-胺)(HPEA)与单异氰酸酯基甲基异胞嘧啶的反应,合成了一系列以脲基嘧啶酮(ureidopyrimidinone,Upy)单元封端的超支化聚合物(HPEA-U).由于Upy单元间形成自识别四重氢键作用,Upy改性聚合物的熔融流变行为表现出了明显的温度和频率依赖性.随着Upy含量增加,聚合物的解缔温度逐渐增加.在低频范围内,随着频率增大,其表观黏度降低,储能模量增加.在临界频率以上,随着频率增大,出现剪切变稠及储能模量迅速降低现象.基于Upy微区结构的剪切破坏及游离Upy单元间的氢键结合,对这种特殊的流变行为进行了解释.A series of prepared by reacting hyperbranched polymers with different contents of ureidopyrimidone （Upy） units were hydroxyl terminated hyperbranched poly（amine-ester） （HPEA） with monoisocyanato methylisocytosine at -OH/-NCO ratios of 1：0.13,1：0.25,1：0.33 and 1：0.5, respectively. The melt rheology of the modified polymers was investigated by using a Physica MCR300 rheometer. Due to the formation of selfcomplementary quadruple hydrogen bonding of Upy groups, the modified polymers demonstrated strong temperature and frequency dependent characters in melt rheological properties, and the dissociation temperature appeared to increase as more Upy units existed in the samples. The results indicated that at the low frequency range, the complex viscosity decreased, the storage modulus became larger as increasing the frequency. However, at the high frequency range,the samples displayed shear-thickening behavior, and the storage modulus decreased sharply to rather low values as increasing the frequency. Meanwhile, the loss modulus seemed to increase as elevating the frequency at all frequency range. Such uncommon rheologica] performance could be explained based on the disruption of Upy micro- domains by shearing force and the formation of quadruple hydrogen bonds between the released Upy units. This investigation is helpful for understanding the theological behavior of Upy contained polymers and designing new dynamic functional materials.

关 键 词：Upy单元 四重氢键 超支化聚合物 流变学行为 

分 类 号：O631.1[理学—高分子化学]